Internal combustion engine



June 15, 1937.

G. V. ANDERSON ET AL INTERNAL COMBUSTION ENGINE 9 She'etsSheet 1 Filed Nov. 11, 1955 3 J w M G/LBEEIMAWDZTJOM.

, 1937- G. v. ANDERSON ET AL 2,083,680

INTERNAL COMBUSTION ENGINE June 15 Filed Nov. 11, 1933 9 Sheets-Sheet 2 1854? BIN f June 15, 1937- a. v. ANDERSON ET AL 2,083,680

INTERNAL COMBUSTION ENGINE Fud Nov. 11, i953 9 Sheets-She et 5 lazy is,

June 15, 1937. a. v. ANDERSON ET AL 2,083,680

INTERNAL COMBUSTION ENGINE Filed Nov. 11, 1953 9 She'ets-Sheei; 5

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June-15, 1937- ca. v. ANDERSON El AL 3,

' INTERNAL COMBUSTION ENGINE Filed Nov. 11, 1933 9 SheetsSheet 7 Fi g.24

June 15,1937.

G. v. ANDERSON ET AL 2,083,680

INTERNAL-COMBUSTION ENGINE Filed Nov. 11, 1935 9 Sheets-Sheet 8 June 15, 1937.

a. v. ANDERSON ET AL INTERNAL COMBUSTION ENGINE Filed Nov. 11, 1935 9 Sheets-Sheet 9 Wax- Patented June 15, 1937 UNITED STATES PATENT orrics 'l'. Bremser, Westmont, N. 1., ner Machine Company, Philadelphia, corporation of Delaware assignors to Lar- Pa., a

Application November 11, 1933, Serial No. 697,560 19 Claims. (Cl. 123-46) The present invention relates to internal combustion engines of the free piston type. By engines of the free piston type is meant engines in which the reciprocating motion of the pistons 5 is not transmitted to a crankshaft or other similar device by mechanical means whereby a deflnite and exact lengthof piston stroke is established. In a free piston engine the length of piston stroke is maintained at a constant magnitude by providing a perfect balance between the power developed in the engine and the power consumed in the machine which is being driven by the engine.

More particularly, this invention relates to internal combustion engines of the free piston type operating on the Diesel or otherthermodynamic cycle in combination with mechanism adapting them to use for pumping purposes or other power utilizing devices of the reciprocating type.

Engines of this type built in combination with power utilizing. devices of the type mentioned have so far not been suitable for operation un-. der wide variations of speed and load.

A purpose of this invention is to provide an power producing unit, in the form of an internal combustion engine, and a power' consuming unit in the form of a reciprocating machine such as a piston type air compressor or pump.

30 A further purpose is-to provide a combination of an engine and machine of the aforementioned types in which the power produced is transmitted to the machine without the use of crankshafts,

r clutches, links or similar devices, in a simple and direct manner.

Another purpose of this invention is to provide a combination of an engine and machine of the reciprocating type and. to interpose rest periods between complete working cycles and in so doing to vary the number of cycles or strokes per minute. In case there is no load demand for the engine, ordinary engines of the free piston type as well as those of conventional crankshaft type have to idle and in idling consume a considerable amount of fuel. The provision of rest periods in the engine forming the subject matter of the present invention eliminates the necessity for idling in operation and therefore results in an unusuallyhigh fuel economy.

A further object of the invention is to absorb a predetermined amount of power, developed within the engine cylinder, in a body of confined r air by compressing this air in an accumulator during the power stroke of the'engine piston unusually compact and eflicient' combination of a and to expand this compressed air to eflect the compression stroke of the engine piston.

A further purpose is to transmit the energy necessary for the compression stroke of the engine piston and the suction stroke of the compressor or pump by interposing a body of liquid between the engine piston and the accumulator piston and to reciprocate this body of liquid in unison with the engine piston and accumulator piston instead of using mechanical connections between these pistons such as rods, levers, links, gears and similar devices.

A still further object is to interpose a body of liquid between the engine and accumulator pistons as aforesaid to provide a medium necessary and adaptable to accomplish the provision of rest periods between working cycles.

An additional purpose is to provide a novel combination of a two cycle opposed piston engine, a. machine for absorbing the engine output and an accumulator with two pistons which are caused to reciprocate in synchronism with one another together with the provision of a hydraulic connection between each accumulator piston and its corresponding engine piston so that the engine pistons reciprocate in 'synchronism with one another by reason of the synchronized movement of the accumulator pistons.

A further object is to provide between the engine pistons and accumulator pistons a body of liquid of a predetermined quantity or .volume and to provide means for maintaining this volume constant and in the case of an opposed piston engine, where two separate bodies of liquid are employed, to maintain the volume of each body of liquid constant and both volumes equal. Another object of this invention is to provide a novel method whereby the position of the engine piston at the end of the power stroke of this piston is maintained within close limits and the provision of means adapted to practice this method.

' A still further object is the provision of novel means in connection with the means for maintaining the local position of the engine. piston at the end of the power stroke, for regulating the amount of fuel injected into the engine cylinder for each power stroke to correspond with 2 s,oss,ceo

means for regulating the duration of the rest periods to make this last mentioned regulation automatic.

A still further purpose is to provide novel means for controlling the speed of a. multicylinder unit in such a manner that a uniform firing sequence is obtained.

Referring to the accompanying drawings. which are made part hereof:

Fig. 1 illustrates a longitudinal sectional view through the center line of an opposed piston engine compressor unit.

Fig. 2 is an end view of the unit shown in Fig. 1.

Fig. 3 is a cross-section taken on line 3-3 of Fig. 1.

Fig. 4 shows an enlarged cross-sectional view of parts of Fig. 1.

Fig. 5 shows a cross-section through the apparatus used to accomplish the rest periods and through the engine speed control apparatus.

- Fig. 6 is a. partial view of Fig. 5 illustrating the rotary valve in open position.

Fig. '7 shows a variation 01 construction of the engine speed control apparatus similar to that shown in Fig. 5.

Fig. 8 shows details of Fig. '7 giving a cross-sectional view of certain parts along line 8-4 of Fig. '7.

Fig. 9 is an end view 9-9 of Fig. 7.

Figs. 10a, 10b, 10c and 10d illustrate diagram matically the functioning of the apparatus shown in Figs. 7, 8 and 9.

Fig. 11 shows a cross-section through a 1'0- tary speed-control valve for a multicylinder unit.

Fig. 12 shows a diagrammatic illustration of the rest period efiected by the rotary speed-control valve.

Fig. 13 shows a diagrammatic illustration of the rest period obtained with a needle type speed control. valve.

Fig. 14 shows a cross-section through a needle type engine speed control valve.

. Fig. 15 shows a typical indicator diagram of the engine.

Fig. 16 shows a typical indicator diagram of the compressor.

Fig. 17 shows a typical indicator diagram of the accumulator.

Fig. 18 shows a partial cross-sectional view of the engine compressor shown in Fig. 1 together with the apparatus to control the volume of fluid in the hydraulic system.

Fig. 19 shows a partial cross-section through the center portion of the unit shown in Fig. 1

but taken along line l9l9 of Fig. 2 and discloses means for driving auxiliary apparatus shown in Figs. 18 and 21.

Fig. 20- shows a partial cross-sectional view of the accumulator shown in Fig. 18 along line Fig. 21 illustrates diagrammatically the fuel pump, the governing device, and the liquid makeup pump and shows a side elevation of the volume control apparatus shown in Fig. 18.

Figs. 22 and 23 are diagrammatic illustrations of typical velocity curves for the engine pisto and connected parts.

70 Fig. 24 shows a longitudinal cross-sectional view of one-half portion of an engine pumping unit oi similar construction as the engine compressor unit shown in Fig. 1. The cross-section is taken along line 24-24 of Fig. 25.

75 Fig. 25 shows an end elevation of the unit about the centerplane l-l.

shown in Fig. 24 and discloses some details in cross-section.

Fig. 26 illustrates diagrammatically an accumulator and hydraulic synchronizing apparatus, showing a longitudinal section through this apparatus. f

Fig. 2'! is a section taken on line 21-21 oi Fig. 26 and also an end elevation of the apparatus shown in Fig. 26.

- the type oi speed control valve shown in Fig. 14.

Fig. 32 shows an engine accumulator with a differential piston.

Fig. 83 shows an engine accumulator with pistons arranged in tandem.

Fig. 1 illustrates a Diesel engine-compressor unit of the type referred to. This unit is of the opposed piston type and is, with the exception of engine cylinder 2, constructed symmetrically In other words, centerplane l| divides the engine-compressor unit into two halves of substantially identical construction. Plain numerals designate the parts forming one-half'of the unit, while the corresponding parts forming the other half have the same numerals with the index Engine compressor unit-The engine consists essentially of the cylinder 2, of known construction used with opposed piston two-cycle engines and the pistons 5 and 5, mounted therein andmoving in opposite directions. Scavenging air ports 3 are located at one end of cylinder 2 and exhaust ports 4 are located at the opposite end. The engine pistons 5 and 5' are shown in their inner position forming between them the cylinder space i, commonly called the combustion space. One or more spray nozzles I, of known construction, are mounted in the side of cylinder 2 in such a manner as to direct a spray of fuel into the combustion space 6. A starting air valve 8, of known construction, permits the initial setting of the engine pistons with compressed air in well known manner. The method of starting the engine is fully hereinafter described. The engine cylinder 2 is held rigidly in the middle of the cylindrical engine casing scavenging and charging air is supplied to the engine cylinder from the scavenging air chambers l0 and chambers Ill receive the air through one or more nonreturn valves diagrammatically indicated at H and of known construction.

The compressors consist essentially of the cylinder sleeves l2 and I2 mounted in each end of the engine casing 9, the cylinder heads I and H containing the suction valves I5 and discharge valves l6, the latter only shown in Fig. 1 but both indicated in Fig. 2, all of known construction, and the compressor pistons i1 and I! mounted slidably in cylinder sleeves l2 and II respectively, The compressor piston l1 and the engine piston 5 are preferably made in one piece and for descriptive purposes numeral I'l refers to that portion of the combined engine and compressor piston which slides in the sleeve i2 and closes off the inner end of the compressor cylinder space l8, while numeral 5 indicates the'portion which slides in the engine cylinder 2. The compressor cylinder space 18 is formed in a-novel manner by the parts l2, l1 and I4, the cylinder head I4 having a ram l9 formed as a cylindrical extension thereof, extending beyond the flat inner face 20 of the cylinder head l4. The ram I9 carries seal rings 2|. The inner bore of piston 5 is machined to fit slidably over ram l8 and rings 2| thus sealing the cylinder space l8 against communication with space 22 on the inside oi piston 5. The inner side of piston N forms, together with the engine cylinder casting 2 and the engine casing 9, the compression space 23 for the scavenging air. Admission of the scavenging air into space 23 is afforded through passages 24 which areradially arranged around the cylinder sleeve l2 and the'casing 9. Space 22 may, if desired, be vented to the atmosphere.

In Fig. 1 the piston I1 is shown in its retracted position, and the scavenging air already has been compressed in space 23 and transferred through passages 25 and the valve I l into the chambers ID. The arrows indicate the direction of flow of the scavenging air.

A cylindrical sleeve 26 is inserted axially into the cylinder head l4 and the ram l9. Longitudinal grooves 28 are arranged around the outer circumference of sleeve 26. This construction is shown in detail in Fig. 3. The grooves 28 communicate with a common, preferably a circular, cavity 29 in the cylinder head I4 and this cavity 29 communicates with passage 30. The inner end of grooves 28 communicate with the inner cylinder space 3|. Near the outer end of sleeve 26 are port openings 32 which efiect communication between the cylinder 33 and the passages 34.

Sleeve 26 is closed off at its outer end by the cap 35 and both are held securely in the cylinder head l4 by the nut 36. Ground faces, or a gasket, afford perfect seal between passages 30 and 34 at the shoulder 31 of sleeve 26 while a tapered gasket 38 prevents leakage along the outer diameter of cap 35.

A differential piston 39 is mounted slidably in the sleeve 26 and is securely attached to the piston 5 by the piston rod 40 and the nut 4!. The

free end of piston 39 is smaller in size than the remainder of the piston and will enter slidably into the pocket 42 of cap 35. A check valve 43,

passages 44 and grooves 91, are provided on the free end of piston 39 and are illustrated in ,a

larger scale in Fig. 4.

A non-return valve 45 permits oneway communication between passages 30 and 34 in the cylinder head I4.

, The two cylinder heads l4 and 14 are held securely against the engine casing 9 by the tie rods 46, which are shown in Figs. 2 and 28 but not shown in Fig. 1. v

Engine stroke release valve.--The piston valve assemblies 50 and 50' are mounted rigidly on the outer sides of the cylinder head l4 and I4. To aflord a: better understanding of the piston valve assemblies 50 and 50 a cross-sectional longitudinal view identical with that shown in Fig. 1 is illustrated as a part of Fig. 5. Figs. 1 and 5 will best be considered simultaneously in 'explaining the piston valves. The valve casing has a passage 52 connecting with passage 34 in the cylinder head l4 and a cylindrical sleeve 53, which has ports 54 arranged radially and which communicate with the annular cavity 55, also formed in the valve casing 5|. Cavity 55 is direct- 1y connected to passage 30. A piston valve 56 slides in sleeve 53 and is long enough to cover theports 54 with a sufllcient overlap of the edges drlcally. The piston 58 is mountedwlidably in the casing 51 and connects with piston valve 56 by means of piston rod 59 which protrudes through the casing 51 and is fitted slidably therein. The stop-collar 66 limits the stroke of piston 58 towards the left and when held against the stop-collar 60 by the spring 6|, the .piston valve 56 fully overlaps the ports 54. Passage 62 forms the connection between the cylinder space 63 and the engine speed control valve I06 shown in detail in Fig. 5, which will be explained later on in the specifications. The valve casing 51 is closed ofl on one end by the plug 64, which also serves as a stroke-limiting stop for piston 58, thus forming the cylinder space 65. Communication between 65 and passage 34 is established by the tubular connection 66. An annular groove 61 in the cylinder bore of casing 51 is overlapped by piston 58 when said piston is in the position shown and the amount of overlap of the edges is the same as the amount of overlap of the ports 'accumulator is meant means for containing pressure fluid to effect the compression strokes of the engine pistons. The accumulator H is cylindrical and has a waterjacket I2 surrounding a cylindrical bore 13 into which are slidably insert ed the double acting accumulator pistons 14 and 14'. The space 15 between the pistons 14 and 14 is filled withair, preferably air under pressure which is initially admitted through the spring loaded valve 98. The end of the piston 14 facing the fluid cylinder space 16 has an extension 16 with a check valve 11 and passages 18 and grooves 19, and its diameter is of such dimension as to permit the extension 16 to enter the cylindrical cavity slidably. The design of extension 16 and the cavity 80 is identical with that shown in Fig. 4 which serves to control the over-stroke of the engine pistons. Piston pin 8| is inserted into the piston 14 and protrudes outside the accumulator H. Elongated openings. 82 through the waterjacket l2 permit unobstructed reciprocating movement of the piston pins 8| and 8t. Fulcrum pins 83 are positioned in the middle between the two pistons I4 and I4 on the side'of the accumulator II and serve as fulcrums for the rocker levers 84. The two arms of the rocker levers 84 are of equal length'and their ends are connected to the piston pins 8| and 8| by rods 85 of equal length and pins 86.

Now, having fully described the major parts forming the engine-compressor unit, the functions of these parts will be explained while the engine is in operation.

To give a better understanding of the operation of a free piston engine-compressor, a diagrammatic illustration of the working cycles of the free piston engine, compressor and accumulator forming the subject matter of this invention are shown in Figs. 15, 16 and 17. The diagrams shown are pressure-displacement diagrams.

In Fig. 15., compression in the engine takes place according to curve 28-0 and the area ABC represents the energy necessary to eifect the compression. Line C-D indicates the pressure rise during. combustion and expansion takes place according to curve DE, while from E to B the combustion gases are being expelled from the engine cylinder.

In Fig. 16 compression in the air compressor takes place according to curve G-H and delivery of the compressed air into the receiver follows line The compressed air contained in the clearance space of the air compressor cylinder expands as indicated by curve IK, while a new charge of air is drawn into the compressor cylinder as indicated by line KG.

In Fig. 1'7, which shows the pressure-displacement diagram of the accumulator, M indicates the initial air pressure in the accumulator cylinder and curve M-N is the compression and expansion line, so that N indicates the maximum compression pressure. A second compressionand expansion curve M' N is shown as a straight line, indicating that the air pressure remains constant or very near constant. This condition is obtained when the volume I5 of the accumulator shown in Fig. 1 is made very large. In that case valve 98 is omitted and replaced by a pipe connection of liberal size to the large compressed airtank. It is, however, necessary that the areas LMNO and LM'--N'O are equal so that the same amount of energy is stored in and subsequently delivered by the compressed air.

Dynamic balance in the engine-compressor unit exists when area BCDE which represents the useful energy developed within the engine cylinder, equals area CHIK which indicates the energy consumed by the air compressor, and when area ABC equals area LMNO plus area IKF.

Operation of engine-compressor unit and its stroke release.In Fig. 1, the engine pistons 5 and 5' and compressor pistons l1 and H are in their innermost positions, while the accumulator pistons 14 and 14' are in their outer positions. The hydraulic pistons 39 and 39' are also in their innermost positions. The combustion space 6 is filled with highly compressed and highly heated air and fuel is being injected into this space by the nozzle 1, fuel being supplied to this nozzle by fuel pump Hill. The chambers 3|, 33 and 16, together with intercommunicating passages are substantially completely filled with a fluid, as, for example, oil, whereas the cylinder space I5 of the accumulator contains air under pressure. The compressor cylinder l8 contains air which is to be compressed and to be pumped to an air receiver 99.

Combustion takes place in 6, the combustion pressure forcing the pistons 5 and 5 apart. Compressor pistons l1 and I1 move toward the cylinder heads l4 and M respectively. The air suction valves i5, shown in Fig. 2, are closed and the air in I8 is being compressed until the outlet valves i6 open, so that, as H proceeds on its outward stroke, air under a predetermined pressure is forced through valves I6 into the receiver 99. The discharge of the compressed air continues until pistons I1 and I1 have come within close proximity of the face 20, coming to a stop without touching it. Since the hydraulic piston 39 is mechanically connected to piston 5, it also will travel outwardly and in so doing will displace fluid and force a portion thereof into cylinder space 10, as hereinafter explained,

thus moving the accumulator pistons 14 and 14' towards each other. The air in 16 will be compressed to a higher pressure. The flow of liquid into I and also the movement of pistons I4 and I4 will cease as soon as pistons 6l1-39 and '|l'39 have come to a standstill as explained. It will be noted that while piston 39 displaces liquid from cylinder space 33 into passage 34, a. fixed amount of liquid will be drawn into 3|. In other words, part of the fluid' displaced by 39 in its outward stroke will flow through non-return valve 45 into passage 30 and subsequently through 29 and 28 into 3|. It is for that reason that only a portion of the fluid displaced by piston 39 flows into 10. As soon as the outward movement of piston 39 is-terminated valve 45 will close again.

Shortly before reaching its outer position the piston 5' will uncover the exhaust ports 4. Gas pressure, in the engine cylinder will be released through these ports into the atmosphere and shortly. thereafter, but before the pistons have terminated their outward movement, the piston 5 will uncover the scavenging ports 3 and air under a light pressure will flow from l0 into the engine cylinder.

All pistons are at a standstill as soon as the engine piston has terminated its outward stroke. A high air pressure is being exerted upon pistons l4 and 14' by the compressed air in chamber 15. This pressure is being transmitted to' the fluid in the hydraulic system of the engine and subsequently the fluid imposes a high pressure upon the piston 39, on the end thereof facing chamber 33. Therefore all pistons have a tendency to move again, this time in the opposite direction, i. e., the accumulator pistons 14 and I4 outwardly and the pistons 39, 5 and I1 inwardly.

Movement of the pistons, in the direction just explained, is prevented since piston valve 56 closes oil the ports 54 and since non-return valve 45 is closed. Therefore the fluid intermediate between valve 56 and chamber 3| cannot escape into passage 34, from whence it came during the outward stroke of 39. The entire fluid pressure exerted upon the outer and larger face of 39 is counteracted by fluid pressure acting upon the shoulder at the other end of 39 and the piston is locked in position.

In order to permit expansion of the air in 15 and subsequent return movement of the pistons, the piston valve 56 has to be moved axially to uncover the ports 54 and permit fluid to escape from chamber 3|. Axial movement of the piston valve 56 is accomplished by making use of the difierence between the pressure of the fluid in passage 34 and the pressure of the fluid in passage 30, the latter being under a higher pressure than that contained in passage 34. Axial movement of the piston valve 56 is effected by connecting passage 3|) with passage 62 and chamber 63. Fluid under high pressure from 30 will exert a high pressure upon piston 58, thus moving this piston to the right and compressing the return spring 6|. Transfer of fluid from 30 to 63 is accomplished by the engine speed control valve I03. This valve is connected to passages 30 and 62 and will be described in detail later on in the specification.

As stated above, piston 58 moves toward the right until it uncovers the annular groove 61. At the same time piston valve 56 will move toward the right and uncover ports 54. The fluid may then flow freely past valve 56 into 34. As

soon as chamber 88 is connected with groove 81 the ,piston 88 and the piston valve 88 will remain open until the flow from chamber 18 in accumulator 1| stops. Chamber 88 of the valve casing 81 is connected with passage 84 by means of the connection 88 so that no liquid can be trapped in chamber 88.

,While piston 11 is travelling towards its inner position it will first cover the passages 24 in the 10 cylinder sleeve 12 and will then compress the air contained in chamber 28 and transfer this air through the passages 28 and the non-return valve ll into the scavenging air chambers 18. At the same time piston II will draw a fresh charge 15 of air into cylinder l8 through the suction valves 18. 1 a

While piston 8 is moving to its inner position it will at first close 011 the scavenging air ports 8, and piston 8' will close 01! the exhaust ports 4. 20 While continuing their movements towards each other, the air charge contained in cylinder 2 between the pistons 8 and 8' will be compressed until the pistons come to a standstill in the position shownin Fig. 1. Fuel will then be injected 2 again and the cycle as described will be repeated. Synchronizing means.-It is evident that it is necessary to synchronize the movement of the pistons 8, i1, 88 and 14 with the pistons 8', I1, 88' and 14'. Fig. 1 shows a means of mechanical 30 synchronization of the pistons 14 and 14' by means of the rocking lever 84 and the connecting rods 88. Since the liquid connecting the pistons 14 and 14' with the pistons 88 and 89' respectively, is under pressure at all times during the 35 engine cycle, it is evident that the liquid takes the place of a mechanical connection between the accumulator piston 14 and 14' and the pistons 88 and 88'. In other words, since the movements of the accumulator pistons are synchronized and since the engine pistons and accumulator pistons move in unison, therefore the movement of the engine pistons are synchronized.

Another means of synchronization is shown in Figs. 26 and 27. a

In Figs. 26 and 27, the accumulator 11 is the same as shown in Fig. 1.

Attached to the piston pins 8| and 81' are the piston rods 88, each one of which carries a hydraulic plunger 81 and 81'. The plungers 81.

- respectively. The casings 98 and 88 are closed off by the covers 9| and 82 through which the piston rods 88 and 88' protrude. Cylinder bores 88 and 89 communicate with each other at each end by means of the passages 98 and 84. The cylinders 88 and 88, and also the passages 98 and 94, are filled with fluid.

It is evident that when plunger 81 moves in the direction of arrow 98, plunger 81' is forced to move in the direction indicated by arrow 88, since fluid is displaced from 88 through channel 94 to the left face of plunger 81' and also from 89 through channel 98 to the right face of plunger 81. Since the volume displacement of both plungers 81 and 81' are equal the plungers are forced to move together, in opposite directions and at the same velocity, thus resulting in a perfectly synchronized movement of the accumulator pistons 14 and 14'. 7

Whereas the form of accumulator 1| illustrated in Figs. 1, 2 and 25 and partly shown in Figs. 18, 20, 21 and 26, represents a preferred form of construction, other forms of accumulators may be employed.

.ber 281.

-with valve 90, Fig. 1.

Modified aeeumfllator.--Fig. 28 illustrates an accumulator 288 in connection with an enginecompressor unit 281 of the same general construction as illustrated in Fig. 1. In this form of accumulator, two cylinders 282 and 282' are arranged side by side and parallel to each other and the pistons 288 and 288, of identical construction and dimensions, are mounted slidably therein. The pistons are rigidly connected with each other by means of rods 284 and 284' and the yoke 288. Centrally inserted through the yoke and parallel to the cylinders 282 and 282', is a guide rod 288, one end of which fits slidably into the cylindrical extension of the common cylinder head 288 whereas the other end fits slidably through and extends outside the center portion of the accumulator casing 288. Stufiflng box 289 prevents leakage from chamber 281. The free end 282 of the guide rod 288 may be used to drive aluxiliary apparatus employed to operate the eng ne. 1

The extensions 288 and 288', and also the dashpots 284 and 284', may be of the same design as illustrated in Fig. 4 and are intended to serve the same purpose.

Fluid is pumped into chambers 285 and 288' from the engine through pipe connections 288 and 288' during the expansion stroke of the engine. Pistons 288 and 288' will move upwards, thus compressing the air contained in the cham- The yoke 288 and the guide rod 288 assure synchronized movement of the pistons 288 and 288'. Expansion of the compressed air in chamber 28l will effect transfer of fluid from chambers 288 and 288 into the engine, thus providing the energy and movement necessary to efl'ect a synchronized compression stroke of the engine pistons.

Synchronization of the engine pistons may be eflected without the use of any linkage by the accumulator illustrated in Fig. 32. The cylinder 888 contains a reciprocating differential piston consisting of two elements 881 and 882 of different diameters. The area of 881 exposed to the fluid in chamber 888 is the same as the area of 882 exposed to the fluid in chamber 884. Chamber 888 is filled with air'under a predetermined pressure admitted to this chamber through valve 888, mounted in cover 881 and which is identical The free end of. 88I has an extension 888 containing passages 889, a nonreturn valve 818 and grooves 811, and fits slidably into the pocket 812 in cover 818. This construction is identical with that shown in Fig. 4 and serves the same purpose. A pin 814 is insorted through 881 and extends outside the cylinder 888 through openings 818. It serves to drive auxiliary apparatus used to operate the engine pumping unit as, for example, the arm I80 of Figs. 18 and 21. Conduits 818 and 811 serve the same purpose as conduits 888 and 888' of Fig. 28 and are to be connected to the engine in the same manner. Since the fluid displacements of 88I and 882 are equal it is evident that synchronized movement of the engine pistons is effected. During the expansion stroke of the engine the air in chamber 888 is compressed to a higher pressure and then expands to eiIect the compression stroke of the engine pistons.

The accumulator illustrated in Fig. 33 will also effect synchronized movement of the engine pistons. The accumulator casing 888 consists essentially of two cylinders 881 and 382 which open at one end into the chamber 888. Pistons 884 and 888 rigidly mounted on a common piston rod 336, reciprocate in the cylinders and divide them into chambers 331, 333, 339 and 390. Chambers 381, 339 and 333 contain air under pressure admitted by non-return valve "I, which is identical with valve 93 of Fig. 1. Chambers 333 and 390 contain fluid under pressure which is a portion of the fluid contained in the hydraulic systems of the engine and conduits 392 and 392' connect with the engine in the same manner as conduits 255 and 253', Fig. 28. Covers 393 and 394 close the accumulator casing 330 and the piston rod 336 protrudes through cover 393. One end 395 of 333 may be adapted to drive auxiliary apparatus used to operate the engine and corresponds functionally to pin 314 of Fig. 32. Since both pistons 334 and 335 are of equal diameter, the same amount of fluid is displaced by them and synchronized movement of the engine pistons is eflected.

Engine speed control valve.Considering how the matter of speed control. Fig. shows how communication is eilected between passages 30 and 34 by means of piston valve 53.

The engine speed control valve may be of the rotary type as shown in Fig. 5. It consists of a valve body. I00 having passages IM and I02 formed therein and also carrying the rotary valve I03. Grooves I04 and I05 are provided in the surface of the rotary valve I03 diametrically opposite each other. Their purpose is to eilect communication between passages IOI and I02 and IN and I02, respectively. Further communication between passages MI and I02 and IOI' and I02 is aflorded by passages I03 and I06, respectively, when the valves I01 and I01, which are being closed by springs I03 and I03, are in open position. Passage IOI' is to be connected to passage 55' in Fig. 1 and passage I02 to passage 62' in Fig. 1, whereas passage IOI communicates with 55 by means of tubular connection I09, and passage I02 leads directly to passage 52 shown in Fig. 5.

Fig. 6 shows the position of the rotary valve I03 when effecting communication between "II and I02 and IM and I02, respectively. The arrows indicate the direction of flow. It should also be noted that communication between IN and I02 and IM and I02 takes place simultaneously so that both portions of the enginecompressor unit operate in synchronism. It has been explained previously that the fluid under pressure transferred from chamber 55 to chamber 53 causes axial movement of the piston 53 and valve 53. It is evident that after the rotary valve I03 has established communication between IN and I02 it will, while continuing its rotation, terminate this communication. At that time the piston 53 has moved axially against stop 64. When piston 53 returns to the position shown in Figs. 1 and 5, it will at first displace fluid from chamber 63 to passage 30 through annular groove 51 and tubular connection 63, until the groove 61 is substantially overlapped by the piston and while continuing its movement until the stop collar 50 terminates the movement of the piston 53, the latter'will displace fluid from 63 to 55 through the one way valve I01.

The rotary valve I03 is rotated by some form of motor, such as electric, hydraulic, pneumatic or other form. Fig. 5 shows a hydraulic motor H0. The speed of rotation of this motor is controlled by regulating the rate of flow of fluid through the motor. The inlet pipe III is connected to the needle valve body H2. The needle valve 3 is mounted slidably in H2 so as to regulate the opening I I 4. Fluid is admitted to H5 by means of passage Hi, the tubular connection H1 and the shut-off valve II3 from an accumulator I11, Fig. 21, referred to later. Axial movement of the needle valve is obtained by movement of the piston 9 which connects to the needle valve by means of rod I20. Piston H9 is mounted slidably in cylinder I2I and divides this cylinder into two chambers I22 and I23. Chamber I22 is vented to the atmosphere and chamber I23 is connected to the air receiver 99 shown in Fig. 1, so that the pressure in I23 is always equal to the pressure in the air receiver 99.. The air pressure upon piston H9 is counter-balanced by spring I24. It. is evident that a reduction of pressure in chamber I23 will result in an axial movement of piston H9 in the direction oi. arrow I25, and also in a movement of the needle valve in the same direction, which will result in an increased rate oi flow of fluid to the hydraulic motor IIO, eilecting an increase in speed of this motor, and a subsequent increase in strokes per minute of the engine-compressor. Valve II3 serves to stop the hydraulic motor IIO which in turn stops the engine irrespective of the position of the needle valve II3.

An important consideration in connection with the regulation of the number of strokes per minute by means of the rotary speed control valve is the minimum rotative speed at which the rotary valve will etlect a rest period after each engine cycle. The slower this speed can be made, the greater will be the ratio between maximum and minimum number of engine cycles per minute.

It is generally known that the time required to perform a complete engine cycle in a free piston engine is a function of the mass of the reciprocating parts and that this time does not vary much with a wide variation of engine loads.

It is evident that when the speed of rotation of the rotary speed control valve is being reduced progressively, tlielength of the time interval during which passages IM and I02 communicate, will increase at the same rate as the speed of rotation decreases. For a certain speed of rotationthis time interval will be equal to the time required for one engine cycle. Evidently this is the minimum speed at which the rotary valve will effect a rest period after each engine cycle.

The area of the passages IM and I02 and the width of the groove I04 have to be comparatively large in order to permit a suiiicient amount of fluid to pass into chamber 63 during the short time available when the engine is operating at maximum speed. Therefore wide passages and grooves are required for maximum speed, resulting in a long time interval of communication between IOI and I02 at slow speed, so that the minimum speed which can be attained with the rotary valve in Figs. 5 and 6is quite high. At slow speeds the groove I04 could be quite narrow since a longer time interval is available for the transfer of fluid into 53 and a narrow groove would result in a shorter time interval for communication of IOI and I02 and therefore in a lesser minimum number of engine cycles per minute. Rotary valve means which provide a slower minimum speed than can be obtained with the design shown in Figs. 5 and 6, without aflecting the maximum engine speed, are shown in Figs. '1, 8, 9 and 10.

Modification of speed control valve-The valve casing 215 is of identical construction as the casing I00 shown in Figs. 5 and 6 and for bell crank 294 and rod 25.

that reason the various passages in 215 are indicated by the same numerals as in Figs. and 6. The rotary valve proper consists of two parts 216 and 211. Part 216 is rotated by the hydraulic motor II8. It has a shaft extension 218, shown in Figs. 7, 8 and 9, and part 211 is fitted rotatably over the extension 218 and both parts 216 and 211 are fitted rotatably into the valve casing 215. Slidaby mounted on the free end of the extension 218 is the collar 219. The key 288 is fitted securely into .the extension 218 and slidably into collar 219, and the latter can be moved axially on the extension 218 by means of the stirrup 28I mounted on the rocking lever 282. 282 is pivoted at 283 in the bracket 284. Collar 219 has arms 285 provided with pins 286. These pins 286 fit slidably into helical grooves 281 out into the free end of part 211 which protrudes outside the valve casing 215. Groove 288 is cut into the part 216 and groove 289 in part 211. Both grooves are of identical dimensions and serve to establish communication between passages IM and I82. For full speed of the engine, these grooves are positioned in line with one another as indicated diagrammatically in Fig. 10a, and when the engine speed is to be reduced the groove 289 is displaced rotatively relative to groove 288. This relative rotation of groove 289 is effected by rotating part- 211 by means of axial movement of the collar 219 which is effected by the stirrup 28I. The speed of rotation of the hydraulic motor H8 is regulated by the needle valve II3 of the same construction as shown in Fig. 5. The needle valve may be operated automatically, as shown in Fig. 5, or by means of the handwheel 298 and the screw spindle 29I. Movement of the needle valveis transmitted to the stirrup lever 282 by means of arm 292, rod 293,

The interconnection just described is such as to bring grooves 288 and 289 'in line with one another when the needle valve H3 is in full speed, or wide open,

position. and will effect rotative movement of groove 289 relative to groove 288 while the needle-valve is being moved to closed, or minimum speed, position.

Rotation of groove 289 out of line with groove 288 will effect a shorter period of communication between passages MI and I82, as best shown in Figs. 10a, 10b, 10c, and 10d. In Fig. 1011 the 'po-' sition of the passages I8I and I82 with relation to grooves 288 and 289 is shown at the moment of the beginning of communication between passages I8I and I82 when the rotary valve rotates in the direction indicated by the arrow.

Fig. 10b illustrates the duration of communication between WI and I82 as indicated by angle 296 which is the amount of angular movement of the leading edge 391, or the trailing edge 298. of the grooves 288 and 289 from beginning to end'of the communication between passages IN and I82. Fig. 100 shows the groove 289 rotated relative to groove 288 and indicates the position of the passages MI and I82 with relation to the grooves 288 and 289 at the time of beginning of the communication between IN and I82. It will be noted that the moment of beginning communication is determined by the leading edge 291 of groove 288 and the moment of terminating communication is established by the trailing edge 298 of groove 289.

Fig. 18d shows the groove 289 in the position it assumes at the moment of beginning communication and the angle 299 indicates the angular duration of communication.

It will be noted that the angle 299- is substantially smaller than angle 295.- In other words,

the duration of communication between passages IM and I82 may be varied considerably.

The rotary speed control valves just described are particularly adapted to regulate the speed of I a multlcylinder engine-compressor unit or engine-pumping unit and to provide an even firing sequence of the cylinders of such a unit.

Referring to Fig. 11, which is a cross-section taken on line II of Fig. 7, normal to the axis of the rotary valve, the valve block 215 is provided. -with four pairs of passages I82 and. I82, I82a control valve can be employed to regulate the speed of a plurality of engine-power units.

Rest period.-To aiford a better understanding of the term "rest period, the diagram, Fig.

12, shows the amount of movement 388 of the engine piston during various time intervals, reference also being had to Figs. 1 and 5 for illustration. No movement takes place during the period' 38I to 382 asduring this time groove I84 of the speed control valve I83 is out of communication with passages I81 and I82. From 382 to 383 said groove I84 is in communication with passages I8I, and I82, thereby allowing transfer of fluid out of chamber 3| throughpassage 38,

chamber 58 and pipe I89, passage I8I, groove I84 and passage I82 into chamber 63, resulting in a slight movement of the engine piston due to the small discharge from chamber 3I. This movement is controlled by the rate of flow of fluid out of chamber 3| and associated passages.

- Fluid flowing into chamber 33 causes piston 58 and its piston valve 56 to be gradually moved until it opens at 383 whereupon fluid discharges freely from chamber 3I and passage 38 through piston 56 to passage 34, thus allowing the engine piston to begin its actual compression stroke ending at 384, but this movement is not con- I trolled by any restricted transfer of fluid. At

38I', the engine piston ends its expansion stroke and a rest period occurs ending at 382'.

Now it will be shown that the number of engine cycles per minute can be varied without interposing a period of absolute standstill of the engine piston at the end of the expansion stroke. In Fig. 12 the period 382 to 383, during which fluid is transferred into chamber 63 to open piston valve 56, is relatively short and in Fig. 13, which also illustrates diagrammatically the amount of piston movement 385 of the engine piston during various time intervals, the

period of transfer 386 to 381 of fluid into chamber 63, to open piston valve 56, takes the place of the period of absolute standstill 38I to 382 and the period of a slight but controlled piston movement382 to 383 in Fig. 12. In other words, the number of. engine cycles per minute is varied by changing the duration 386 to 381 of the fluid transfer period to effect opening of piston valve 56. The amount of movement of the engine piston during the period 333 to 33'l'is so small, that the air charge in the engine cylinder is not being compressed as yet, since the exhaust ports and scavenging air ports 3 remain open 5 during this movement. In other words, the compression stroke of the engine pistons has not yet begun, and the engine piston merely moves into position 331 to get ready for the compression stroke. Therefore, since the movement 333 to 331 is immaterial as far as the actual compression stroke of the engine pistons is concerned, it is also termed rest period.-

A means to sheet the last named rest period is disclosed in Fig. 14. A valve-block 3I3 has passages 3H and 3I2 which lead into chamber 3I3. .A differential springloaded needle valve 3I4 is mounted slidably in 3I3 and is held in closed position by spring 3I5, as long as there is equal fluid pressure in 3H and 3l2. The lift of the needle valve 3, caused by an increase in fluid pressure in 3I2 and chamber 3I3, is limited by the adjustable stop pin 3I5 and the amount of lift is indicated by 3Il. The amount of lift 3I'l is varied by means of screw 3I3 and handwheel 3I9, but may also be varied by automatic means, if desired. Port 323, leading from 3I2 into 3, is closed by non-return valve 32I. nection I39, Fig. 5, is connected to passage 3I2 and passage 3 leads into 62. Increase in fluid pressure in 3l2 will open needle valve 3l4, thus permitting flow of liquid into 3, which will effect opening of valve 53. Variation of the lift 3Il of the needle valve will varythe time required to open valve 53 and thus vary the duration of the rest period. Non-return valve 32I serves the same purpose as valve I31, Fig. 5. Each engine-half can have a separate speed control valve and both valves are then adjusted to provide the same amount of lift 3ll and simultaneous variation of the lift is effected by transmitting rotation of screw 3I3 to the same screw of the second valve by customary means, such as gears and rods, or by sprockets 322 and chain 323.

In reference to Fig. 14 it has been stated that the manual control of the lift 3| 1 of the difierential needle valve 3 I4 could be replaced by automatic control.

In Fig. 31- the screw spindle 3Il has a gear 353 meshed with a tooth rack 33L The latter ton 353 divides the cylinder 354 into two chambers 355 and 356. Spring 351 acts as return spring for piston 353. Chamber 355 is 'vented to the atmosphere while air is admitted to chamber 353 through port 358 from the air receiver 33 (Fig. 1) or the high pressure liquid receiver 339 (Fig. 30). Increase of pressure in chamber 353 will cause movement of piston 353 in the direction of arrow 359 and tooth rack 35I will rotate gear 353 and screw spindle 3I8, which latter will move downward and reduce clearance 3l'l. A smaller lift of needle valve 3I4 will result andthis will effect a decrease in engine speed.

Method of starting and stopping engine-To put the engine in operating condition, air at a predetermined pressure, which is the minimum normal working pressure of the accumulator, in-

dicated by L--M in Fig. 17, is admitted to cham- Tubularv conis attached to the rod 352 of the piston 353. Pisnormal, for example, due to leakage past the pistons 14 and 14', the leakage will be replenished automatically through the spring-loaded nonreturn valve 93. When the engine and accumulator pistons are in the position shown in Fig. l, compressed air is admitted into the combustion space 3 of the engine through valve 3. The engine pistons will move outwardly and the accumulator pistons inwardly thus compressing the air in 13 to a higher pressure. When the engine pistons have reached their outward position, they will be retained in this position since the piston valve 53 of Fig. 5 is closed and since the speed control valve is in closed position. In the rotary speed control valve shown in Fig. 5, the rotary valve I33 can be set in closed position by rotating it with hand wheel 433 until the pointer 43I, attached to the valve I33 registers with the fixed pointer 432, which is attached to the valve casing I33. The speed control valve shown in Fig. 14 can be closed by hand wheel 3I3. The engine isnow ready to start.

Starting is eiiected with the speed control valve I33 (see Fig. 5) by admitting fluid to the hydraulic motor 'II3 through the valve H3, or if a speed control valve such ,as shown in Fig. 14 is 'used, by opening it with the hand wheel 3I3. In order to stop the engine the speed control valve I33 is placed in closed position. Whereas all internal combustion engines known are stopped by cutting off the fuel supply, the engine described in this invention can be stopped without cutting off the fuel supply.

To explain this feature reference is made to the rest period explained in preceding paragraphs. If the speed control valve is in closed position and as long as it is kept in this position, the engine pistons will be retained in their outward position. Therefore, under normal operating conditions, the engine pistons will always stop in the outward position. If under abnormal conditions the engine pistons should stop in their inner position, that is, the position shown in Fig. 1, they will have to be moved to starting position by compressed air, as explained, before starting can be effected.

Constant volume of fluid in hydraulic 811stem.-An important consideration for continuous successful operation of the engine-compressor unit is the provision of means to maintain a constant volume of fluid in the hydraulic system of the engine.

Referring to Fig. 18, it will be noted that onehalf of the unit shown in Fig. l is illustrated with particular regard to the hydraulic system. The same reference numerals are used in Fig. 18 as in Fig. l for the same parts.

An arm I33 is rigidly attached to piston pin 3I and has a link I3I attached to its free end. This link is connected to the rocker lever I32 by means of pin I33. A rod I34 is mechanically connected to the compressor piston II as shown in Fig. 19. Rod I34 carries arm I35 and the free end of this arm is connected to the rocker arm I32 by means of link I36 which is connected to I32 by pin I31.

A piston valve I33 is slidably fitted into valve body I39 forming the chambers I43 and I therein. which are closed oil by covers I" and I48. When in its normal or fully closed position the piston valve I33 overlaps the ports I42 and I43 which are connected together and communicate with port I44, leading to the accumulator chamber I3, which forms part of the hydraulic system of the engine. Furthermore, chamber I48 is connected by means of passage I45 to a source of supply of fluid under pressure. This source of supply I11 is shown in Fig. 21. Chambr I4I opens to a sump by means of port I45. The piston valve is attached to the rod I48 to which is pivoted the rocker arm I32 by means of fulcrum pin I58. The pin I50 is located at such a point of the rockerarm I32 that the length ratio I50-I33 to I50I31 is the same as the ratio between the length of stroke of the accumulator piston 14 and the length of stroke of pistons 5, I1 and 35. Therefore, it will be understood that as long as the volume of liquid in the hydraulic system positioned between the accumulator piston 14 and the hydraulic piston 35 is such as to result in the positions for pistons 14, 5, I1 and 38 as shown in Fig. 18, the fulcrum point I50 will assume the position shown in Fig. 18 and will remain in this position while the engine and accumulator pistons reciprocate, provided that the volume of the fluid in the hydraulic system remains unchanged. Should the volume of liquid be decreased, for instance, on

account of leakage, then the fulcrum pin I50 will move in the direction indicated by arrow II,

resulting in an axial movement of the pistonvalve I35 in the same direction, uncovering port I42 and permitting fluid under pressure to enter into the chamber 10, resulting in an increase in volume of the fluid in the hydraulic system. As the volume increases, the fulcrum point I50 and valve I35 will move in the direction I52 until the piston I35 closes the port I42, at which time the volume of the fluid in the hydraulic system is restored to normal. Should the volume of the fluid in the hydraulic system be increased above normal, thnfulcrum point I50 will move in direction I52 causing the piston valve I 38 to uncover port I43 which will result in a drainage of fluid from chamber into the sump, since the liquid in the hydraulic system is under pressure at all times when the engine is in operating condition. This drainage is terminated by movement of pin I 50 to its normal position as shown in Fig. 18. V

Referring to Fig. 19, it will be noted that the rod I34,-also shown in Fig. 18, is attached mechanically to the inner end of the compressor piston I1 by means of the hook I55 and slides in guides I55. Openings I51 in casing 8 permit movement of arm I35 which protrudes outside the casing 8. The apparatus to control the volume of the fluid in the hydraulic system, shown in Fig. 18, is also employed to perform the same duty for the other half of the engine-compressor unit. In Fig. 19, rod I34 serves to actuate this apparatus. Later on in the specifications, reference will again be made to Fig. 19 to explain the remaining parts. In Fig. 20, is illustrated how the arm I30 referred to in Fig. 18, is attached to the accumulator piston pin 8|.

Fuel system.-In Fig. 21, the fuel injection pump I50 is of well known construction and supplies fuel under pressure to the spray-nozzle 1, Fig. 1. The fuel pump is actuated by tappet I 5| which rides on the cam segment I52. This cam segment I52 is pivoted by pin I53 held in the sides of casing I54. A connecting link I55 is pivoted to the cam segment I52 by means of pin I55 on one end and its other end is pivoted to rocker arm 54 by pin 55. It will be remembered that rocker arm 84 is oscillated by the accumulator pistons 14 and 14', by means of the rods 55 and 85'. In. Fig. 21 the rocker arm 84 is shown in the position which corresponds to the inner position of the engine pistons 5 and 5', Fig. 1. -It will also be noted that the cam segment I52 has terminated its oscillation In the direction indicated by arrow I51 and that the tappet I5I has been brought to its highest position by the cam nose I58, which forms part of the perimeter of the cam segment I52. In other words, the fuel pump is being or has just been actuated and fuel is being or has just been injected into the engine cylinder. On the subsequent expansion stroke of the engine pistons, the accumulator pistons will move forward, and oscillate the rocker arm 54 in the direction indicated by arrow I55. The amount of oscillating movement is indicated by angle I10. The cam segment I52 will also oscillate about pin I53, so that the tappet I8I will follow the cam nose I55 downward, thus effecting the suction stroke of the fuel pump.

Also illustrated in Fig. 21, is the fluid makeup pump I which is of the well known plunger type. It is actuated by the plunger rod I15 which is connected to one of the piston pins 8I of the accumulator piston 14'. Fluid under pressure is pumped into the constant pressure chamber I11 which'is attached to the outlet of pump.

I15. Constant pressure of the fluid is obtained by means of the spring-loaded relief valve I15, of known construction. An outlet I18 is provided in I11 and serves to transfer fluid under pressure to the various auxiliaries, some of which have been described already.

A very important consideration in connection with the fuel injection pump I 50 is' the regulation of the amount of fuel pumped and injected into the engine cylinder for each power stroke of the engine; 7

In the type of fuel injection pump shown, means for regulating the amount of fuel pumped are provided in the form of the control rod I1I which can be moved axially, the arrow I12 indicating the direction of movement resulting in an increase of the amount of fuel pumped. Pin'I13 on control rod I1I serves to form the connection of this control rod with the governor apparatus. which will now be described.

A bracket I50, attached to the accumulator 1 I, carries two cylinders I8I and I82, into which are slidably inserted pistons I53 and I84, the piston rods I55 and I55 protruding through the closed upper ends of the cylinders I8I and I 52,

respectively. Pivoted to the end of the rods I85 and I55. by means of pins I88 and I88, is the differential link I51. At a fixed point I80 of the differential link I81 ,is pivotally attached the connectingrod I 8|, the other end of which is connected by pin I83 to one arm of bell-crank I82. The other arm of I82 is slotted to fit I13 and moves control rod I1I. The chamber I85 of cylinder I8I has an opening I85 which serves to admit air from the air compressor receiver 89,

Fig. 1, thus exerting at all timesthe air pressure in the receiver upon piston I 53. This pressure is counteracted by spring I81 and the spring will be compressed more with an increase inair pressure in chamber I85, so that a certain predetermined normal position of the piston I53 results from a certain flxed and predetermined air pressure in the air receiver. Also the linkage connecting piston I53 with the fuel pump control rod is adjusted so that a certain fixed and predetermined amount of fuel is injected into the engine corresponding to a certain flxed and predetermined air pressure in the air receiver.

In the foregoing description of the governor apparatus, it has been assumed that point I58 remained in a fixed position, for instance, that shown in Fig. 21. That being the case, it is obvious that an increase of air pressure in the air receiver will result in an increased amount of fuel injected into the engine.

Though the injection of fuel, when regulated by the air pressure in 99, is accurate, it has been found that it is not accurate enough to assure, at all times and under all operating conditions, the same terminal position of the power stroke of the engine pistons.

In any engine, the power necessary to overcome the internal friction and other losses, varies. For instance, more power is required to 5 compensate for the losses referred to when an engine of the type described is relatively cold than when it has attained its normal working temperature.

Therefore, the auxiliary cylinder I82 isrprovid- 20 ed to give an auxiliary fuel regulation to compensate for thevariation of the amount of power lost in the engine under varying operating conditions. Variations in frictional and other losses in the engine will result in a variation of the length of piston stroke and particularly in a variation of the terminal position .of the engine pistons at the end of the power stroke.

Chamber 200 of cylinder I82 is filled with fluid under pressure and this pressure, acting on the underside of piston I82, is counter-balanced by the adjustable spring 20I. Piping 202 connects chamber 200 with the valve block 202, which is preferably mounted on the side of the engine casing 9. A valve spindle 204 is slidably fitted into the valve block 203, and is reciprocated by means of the arm 205 and the tubular rod 200, which latter is mechanically attached to piston I1 as shown in Fig. 19.

An annular groove 201 is provided in valve spindle 204 and four annular grooves are provided in valve block 203. Groove 208 connects with passage 200, to which is connected the fluid supply tubing I19. Grooves 2 I0 and 2 are in communication with tubing 202 by means of passages 2I2 and 2I3. Groove 2 is connected to the sump. The length 2I5 of groove 201 is greater than the distances 2I6 and 2I1 between the grooves 208 and H0, and 2H and 2 respectively.

Therefore, if the valve spindle 204 moves in the direction of arrow 2I8, the groove 201 will first permit fluid under pressure to pass into chamber 200 by means of passages 208, 2I2 and tubing 202, and then allow fluid under pressure contained in chamber 200 to pass from this chamber into the sump by way of tubing 202, and the passages 2I3, 2H, 2 and 2I9. While the spindle valve 204 returns to the position indicated in Fig. 21, corresponding action of draining and filling chamber 200 will take place and, at the time of the engine cycle when fuel injection occurs, piston I84 will have assumed a fixed predetermined position. It is evident that an increase in volume of chamber 200, and a corresponding upward movement of piston I84, will take place only when the amount of fluid transferred into chamber 200 is greater than the amount of fluid drained therefrom.

Fig. 22 represents velocity-stroke diagrams of the valve spindle 204, indicating the velocity of the valve spindle at various positions during the expansion stroke of the engine, whereas Fig. 23 illustrates the same type of diagrams during the compression stroke of the engine.

The same numerals and letters are employed in Fig. 23 as are used in Fig. 22 for corresponding curves, points and values but the numerals and letters in Fig. 23 are provided with the index For instance, curve 220' in Fig. 23 corresponds to curve 220 in Fig. 22. In Figs. 22 and 23 curves 220 and 220' represent the normal velocity curves of the valve spindle 204, which indicate that the valve spindle, and therefore also the engine pistons,

come to a stop at 222, which is assumed to be the point of normal termination of the expansion stroke and incidentally the point of normal beginning of the compression stroke.

Curves 223 and 223' indicate a velocity higher than normal resulting in a longer engine stroke, as indicated by point 224, and curves 225 and 225' show a velocity slower than normal, resulting in a shorter engine stroke as indicated by point 228. Now, 221 represents the portion of the strokeof the valve spindle 204 during which groove 201 permits filling of chamber 200, and is therefore termed filling period, while 228 desighates the portion of the stroke during which groove 201 permits draining of chamber 200 and is therefore termed draining period. It will be noted that the mean piston velocities V1, V2 and V3, during the filling periods 221 and 221'. do not vary much from one another whereas a distinct difference in magnitude may be observed between the mean piston velocities V4, V5, and Va during the draining periods 228.

The duration of the filling and draining periods 221 and 228, and the adjustment of spring 20I, are such that with a normal length of stroke, and with the velocities of the valve spindle 204 following curves 220 and 220, the amount of fluid transferred into chamber 200, during the filling periods 221 and 221', is equal to the amount of fluid drained from 200, during the draining periods 228 and 228', so that there'is no change in position of point I88 and consequently no change in fuel regulation.

If, however, the piston stroke should be shorter than normal and the velocity of the valve spindle should follow curves 225 and 225', respectively, then the largely decreased mean velocities Va and V6 would result in a longer duration of the draining periods 228 and 228', whereas the duration of the filling periods 221 and 221' would not be prolonged in proportion, due to the relatively small decrease in mean velocity V3 and V3. Therefore the volume of fluid in chamber 200 would decrease, resulting in a downward movement of piston I84, which would bring about an increase in the amount of fuel injected, so that the subsequent expansion strokes would terminate again at the normal point 222..

If, however, the stroke of the engine pistons should become greater than normal, the mean piston velocities V2 and Van during the draining periods 228 and 228', would increase decidedly above normal, whereas the mean velocities V2 and V2, during the filling periods 221 and 221', are not in the same proportion above normal as V3 and V3. Therefore, the filling periods 221 and 221' would not be decreased in proportion to the draining periods 228 and, 228' and an increase in volume of fluid in chamber 200 would result, bringing about upward movement of piston I84 and a decrease in amount of fuel injected into the engine cylinder, so that subsequent expansion strokes would terminate again at their normal point 222.

Controlled engine overstroke.-Now, referring to Figs. 1 and 4, it has been explained that the free end of piston 38 will enter into the pocket 42.

Under normal operating conditions, the engine stroke is terminated before piston 33 enters pocket 42 appreciably, but it may, under abnormal conditions, do so. Referring to Fig. 4, it will be noted that one or more narrow grooves 91 are cut longitudinally on the circumference of the extension of piston 39. These grooves are of such cross-sectional area that the fluid trapped in pocket 42, under a high pressure, shall escape at a controlled variable rate or flow, whereby the fluid pressure in pocket 42 may beheld substantially constant during the period of over-stroke. The same means are employed to terminate the outward stroke of the accumulator pistons in case they tend to over-stroke; see 16, 11, 18 and 20 the engine cylinder 6, or accumulator cylinder 12,

become excessive.

Hydraulic pump application.Figs. 24 and 25 illustrate the application, for pumping of liquids, of an opposed free piston engine of the type already described. The engine proper is constructed in every detail exactly like the engine illustrated in connection with the air compressor. For reasons of simplicity, only one-half of the engine pumping unit is illustrated, this unit being constructed symmetrically about line CC. The engine piston 5 and the scavenging air piston 230 are preferably made integral and the flatannular shoulder 231 of the'piston 230 carries the pump plunger rods 232, which are attached to 23l by bolts 233. Preferably two or more pump piungers 234 are employed. These plungers are of known construction and are fitted into pump cylinders 235 which are fitted into cylinder head 236 and bolted thereto by bolts 231 shown in Fig. 25. A common manifold 238 connects the two pump cylinders 235 and is attached thereto by bolts 239. Suction valves 240 and discharge valves 2 4l, ofknown construction, are fitted opposite each other in the middle of manifold 238, and are best shown in Fig. 25. The discharge pipe 242 leads to a liquid receiver, not shown on the drawing, but the use and arrangement of which, is well known in the art. The construction of cylinder head 236 differs from that of cylinder i4, shown in Figs. 1 and 2, only in that it does not have any inlet and outlet valves I5 and I6 but carries the pump cylinders 235. The construction of the extended portion 243 of the cylinder head 236 difiers from the construction of the so-called ram IS in that it does not carry any seal rings 2|, as shown in Fig. 1. Therefore, chambers 244 and 245 communicate with each other through the annular clearance space 246, formed between the outer diameter of the extension 243 and the inner bore of piston 5. The chambers 244 and 245 are preferably vented to the atmosphere. The cylinder head 236 is held against the engine casing 9, which is of the same construction 'as Fig. 1, in the same manner as the cylinder head l4, namely by tie-' rods 46 shown in Fig. 25. The operation of the engine pumping unit is the same as that of the compressor. unit, and auxiliaries necessary for operation are the same as already illustrated and described. In the governor apparatus, illustrated in Fig. 21, and in the speed control apparatus,

latter is connected to the discharge pipe 242 iilustrated in Fig. 24.

Locomotive application-Fig. 29 illustrates the application of a free-piston engine-compressor unit to produce the driving medium for operation of a piston-type locomotive drive. A chassis 325, has wheels 326 which are driven by the cylinders 321 provided with the customary valve gear and reciprocating pistons connected to the wheelsby rods 328.

The driving medium for the cylinders 321 is compressed air which is produced by the enginecompressor unit 329, which is of the construction shown in Figs. 1 to 23. The compressed air is stored in' the receiver 330, entering the latter through pipe connection 33l. Pipe connection '332 serves as inlet for the compressed air to the .cylinders 321 and pipe 333 as outlet or exhaust pipe from the cylinders.

Pipe 334 is the exhaust pipe for the internal combustion engine which forms part of the engine-compressor unit 329;

A plurality of engine-compressor units 323 may be employed instead of a single unit.

In Fig-30, a plurality of engine pumping units 335 are used to supply liquid under pressure for use in a hydraulic motor 336 of known construction. This motor 336 drives the wheels 331 of the chassis 336 of a vehicle for traction purposes, such as a locomotive. Liquid, such as oil, is supplied under high pressure from the engine pumping units 335 into a high pressure receiver 339, by means of the manifold 340, and is then transferred, by means of pipe connection 341, into the hydraulic motor 336. After having delivered its energy to the hydraulic motor 336, the liquid leaves the hydraulic motor at a reduced pressure and is discharged by means of pipe 342 into the low pressure receiver 343, whence it will again enter the pump cylinder of the engine pumping units 335 by means of the inlet pipes 344. Therefore the same liquid is being circulated continuously.

Simultaneous speed control of the four units 335 can beobtained by the use of a speed-control valve as shown in Fig. 11 or by separate speedcontrol valves 345, coupled together by shafts 346 and driven by a common motor 341, Fig. 30.

The same arrangement of high-pressure and low-pressure receivers can be used in connection with the application of engine-compressor units to produce a driving medium suitable to propel a vehicle for traction purposes. The advantage of the high-pressure and low-pressure receivers will be obvious to those skilled in the art of expansion engines for traction purposes, when considering that, when a late cut-off is used in the expansion engine, the exhaust pressure of this engine is excessively high and represents a total waste of energy unless double, triple or quadruple expansion is employed, which, however, results in a very intricate and costly expansion engine.

In the case of a late cut-off in the expansion engine the pressure in the low-pressure receiver may be nearly equal to the exhaust pressure of the expansion engine and during the suction stroke of the air compressor, forinstance, air under pressure will fill the compressor cylinder thus eliminating any substantial loss when the air is leaving the expansion engine.

If a driving medium of great density, such as aliquid is employed in an application such as shown in Fig. 30, the power output of the motor 336 can be regulated by varying the power out 

